In an LCD device, LED backlight is increasingly popular with LCD device manufacturers depending on its advantages of lightness and thinness, good resistant of impact strength and vibratility, good color rendition, pollution-free and being droved by low voltage and direct current. In an LED backlight, a lighter edge-lighting LED backlight attracts more attention. And the LED backlight in a small and medium-sized LCD is rapidly replacing cold cathode fluorescent lamp (CCFL) to become a mainstream backlight.
In the prior art, structure of the edge-lighting LED backlight is shown in FIG. 1. The edge-lighting LED backlight includes: up-frame 11, back-frame 12, printed circuit board (PCB) 13, LED 14, light guide plate 15, bottom reflecting plate 16 and optical model 17. The LED 14 is fixed onto the PCB 13, and light emergence plane faces directly to side surface of the light guide plate 15. The light emitted from the LED 14 is guided by the light guide plate 15 and is diffused by the optical model 17 to provide light source for a liquid crystal layer. The bottom reflecting plate 16 reflects light leakage from the LED 14 so as to make full use of the light emitted from the LED 14.
However, to a large-sized LCD with the size of larger than 19″, the quantity of the LED used by the LED backlight increases remarkably, which is as shown in FIG. 2. An edge-lighting LED backlight lamp includes PCB 21 and LEDs 22 set thereon. With increase of the size of the LCD, the needed LEDs 22 also increase. As for the large-sized LCD which uses the LED backlight, only the backlight cost thereof exceeds at least 5 dollars than that of the CCFL. Therefore, the LED backlight in the large-sized LCD with the size of larger than 19″ has the advantages of lightness and thinness, and pollution-free etc., but it is difficult to achieve mass production as the cost is more expensive.